Australian billionaire Mike Cannon-Brookes described the move as "a bargain for Sydney".

Mr Buckingham, who was once a councillor with Orange City Council, said the transport loop would be "the envy of the world" and benefit regional cities.

"You could live out in the beautiful western region of NSW, enjoy the lifestyle, clean air and national parks while commuting into jobs centres of Penrith and western Sydney," he said in a statement.

"The infrastructure plan takes the pressure off traffic congestion and resources in Sydney, while providing a lifeline for our regions."

The NSW Farmers' Association said it was delighted to see "its" idea for the Blue Mountains tunnel grab the attention of two of the world's tech billionaires and urged NSW MPs to look into it.

"One of the biggest challenges to growing the state's food economy is the inadequate east-west transport connections between the food bowl that is western NSW and Sydney," president James Jackson said.